In a previous post, we discussed why some research studies require that participants include only males while others may be only for females. A variety of reasons are behind this type of selection criteria, based on what the trial is for, what phase it’s in, and what other studies may have already been completed. These factors also apply to race. Race (and other criteria, such as age) applies when either the disease that is intended to be treated is characteristically one of a specified race or because the group to be treated for the disease includes a substantial number of patients in that population. An additional factor is that not enough studies including the specified race have been conducted, so more research is required.
Scientists estimate that, in the human race, there are at least 15 million genetic polymorphisms and an undefined subgroup of variations in normal and disease traits. Polymorphisms are basically genetic variations, meaning that there are two or more alternative forms of the two alleles that make up the same segment of DNA. The most obvious example of this type of genetic variation is the separation into male and female. Another is blood type. Regarding disease, according to the article “The Importance of Race and Ethnic Background in Biomedical Research and Clinical Practice” as published in the New England Medical Journal, “…the change of only a single base pair is required to cause many well-known inherited diseases, such as sickle cell disease, or to increase the risk of common disorders, such as Alzheimer’s disease.
“Studies in population genetics have revealed great genetic variations within racial or ethnic subpopulations, but also substantial variation among the five major racial groups” defined by the 2000 U.S. Census: black or African American, white, Asian, native Hawaiian or Pacific Islander, and American Indian or Alaskan native, the article goes on to state. Some disorders, called Mendelian disorders, are controlled by a single gene mutation that is inherited. Examples of these include sickle-cell anemia, Tay-Sachs disease, cystic fibrosis, and xeroderma pigmentosa. These disorders occur in less than two percent of their populations and are nearly always race-specific; for example, numerous mutations occur uniquely in Ashkenazi Jews, French Canadians, the Amish, and European gypsies. Per the referenced article, “This is because such populations descend from a relatively small number of founders and have remained endogamous for a large part of their history.”
Some other diseases, especially those that are most likely due to multiple genes plus environmental factors, are more difficult to understand, but some do point to racial differences. Susceptibility to some diseases are associated with specific polymorphisms in some races, which are not found at all in patients with the same disease but that are of another race. And some of these polymorphisms occur in all groups, but with highly variably frequency from race to race. Even when a variant that causes a disease occurs in all groups, the effect of that variant can vary according to race. Additionally, race can be a determining factor for how well a patient responds to medications and treatments for the condition.
A final factor in requesting certain races for a study is due to the fact that racial and ethnic minorities have been, and continue to be, underrepresented in many studies and are therefore not adequately sampled. Important differences cannot be uncovered, identified, and intervened with in the groups in which they are needed. “You can’t determine what therapies will work unless they’re in a study,” said Dr. Jonca Bull, associate commissioner of minority health with the U.S. Food and Drug Administration.
For all of these reasons, certain studies or clinical trials may require participants be of a specified race. It may be to supplement prior research completed without significant sampling from that race; it may be due to the prevalence of the indication in one race or another; or it may be to ascertain differences in the effectiveness of medications and treatments within a certain race.
Meridien Research is currently conducting research studies that may require participants be of a select race. For more information or to see if you or someone you know may qualify to participate, please contact us today at 1-888-777-8839.